USDA's Natural Resources Conservation Service proposed the changes late last year on direction from the 2014 Farm Bill.

The CSP covers nearly 70 million acres, USDA says. It is intended to help producers install conservation-minded enhancements on their farms. Participants earn CSP payments for conservation performance – the higher the performance, the higher the payment.

According to the NRCS, changes include tweaks that make the rule easier to read and understand. CSP changes also:

Jan. 20 is last day to provide comments on Conservation Stewardship Program changes

• Limit eligible land to that in production for at least four of the six years preceding Feb. 7, 2014.

• Require contract offers to meet stewardship threshold for at least two priority resource concerns and meet or exceed one additional priority resource concern by the end of the stewardship contract.

• Allowing enrollment of lands that are protected by an agricultural land easement under the Agricultural Conservation Easement Program.

• Allowing enrollment of lands that are in the last year of the Conservation Reserve Program.

The Center for Rural Affairs praised the changes in the rule that allow supplemental payments for farmers who improve their resource-conservation crop rotation, a departure from previous policy that only provided supplemental payments to farmers who adopted these rotations for the first time.

The National Sustainable Agriculture Coalition, though supportive of the CSP mission, says there are a few changes in the proposal that should be considered carefully.

According to NSAC, the changes skew the program toward first-time conservation, giving already established conservation projects a disadvantage.

"This has the unintended effect of penalizing some of our nation's best conservation-oriented farmers by keeping them out of the program or providing them very low levels of support," NSAC said, "sending the unmistakable message that a conservation ethic should wait for government sanction."

NSAC also said it had concerns with the CSP's accessibility to beginning and small-acreage farmers, suggesting the program still has loopholes that skirt the farm bill's per-farm payment limits.

"CSP is unique because it takes a forward-thinking, whole-farm approach to conservation by investing in both ongoing maintenance of existing conservation as well as new, advanced conservation," said NSAC Policy Specialist Sophia Kruszewski. "But if changes aren't made, we risk losing some of the most innovative, conservation-minded farmers from the program."